Tinnitus is the sensation of a sound in the ear or head that is not being produced by an external source. Tinnitus often takes the form of a hissing, ringing, roaring, chirping or clicking sound which may be intermittent or constant.
Tinnitus affects about 10-15% of the adult population. More than two-million Americans are debilitated with tinnitus to the point where it affects their daily functions, including job performance, and personal relationships. Furthermore, the prevalence of tinnitus increases with age, and the demand for tinnitus treatment will significantly increase in the near future.
One approach for treating tinnitus is disclosed in U.S. Pat. No. 6,610,019 to Choy. Choy discloses an apparatus for treating tinnitus patients comprising a sound generator having adjustable frequency and amplitude controls for selecting an output tone having a predetermined frequency and amplitude, a pair of headphones to be worn by the patient for coupling the output of the sound generator to the patient to enable the patient to subjectively match the output tone of the generator to the patient's tinnitus tone, and a phase shift network for selectively shifting the phase of the output wave form of the sound generator through a plurality of discrete incremental phase shift steps. The phase shifted output wave is selectively connected to the tinnitus patient via the headphones to effect phase shift cancellation between the output of the generator and the patient's tinnitus tone. The apparatus resides in a doctors office. Consequently, there is a need for a portable apparatus for treating tinnitus that may be carried by a user suffering from tinnitus.
U.S. Pat. No. 5,167,236 to Junker discloses a portable tinnitus masker in the shape of a hearing aid carried behind the ear. The tinnitus masker includes a sine wave generator, a square wave generator and a potentiometer used as a frequency controller. Am adding device alternately feeds the sine wave signals or the square wave signals to a variable gain amplifier. The output signal from the amplifier is connected to an earphone that produces an audible signal that is led to the hearing channel.
U.S. Pat. No. 5,795,287 to Ball et al. discloses a portable tinnitus masker for use with direct drive hearing devices. A signal generator includes multiple user adjustable controls. The adjustable controls allow a user to select characteristics of the signals that the signal generator produces, with the signal corresponding to sounds the user will perceive to mask the tinnitus. In one embodiment, adjustable control allows a user to select the frequency of a primary tone. As the tinnitus sound is often a pure tone, the tinnitus sound may be masked by an audible signal that is 180 degrees out of phase with the tinnitus sound. In this manner, the tinnitus sound is effectively canceled out by the direct drive hearing device that receives the audible signal that is 180 degrees out of phase with the tinnitus sound.
Even in view of the advances made in providing portable devices for treating tinnitus, there is still a need to improve such devices.